The TK-3 (TK) and TKS light turretless reconnaissance tanks, commonly called tankettes (in Polish: tankietka), were the most numerous armoured vehicles of the Polish Army at the outbreak of World War II in September 1939. Their number of over 500 vehicles constituted formally a significant tank force. Unfortunately, they were not fully capable tanks, and, apart from few cannon-armed ones, could not fight against other armoured fighting vehicles. Also weak armour made them defenceless against any anti-tank weapons. However, using their advantages like manoeuvrability and small silhouette, they were still valuable reconnaissance vehicles and could fight efficiently against manpower, especially when using the element of surprise. In need, they had to support Polish local attacks and counterattacks, often suffering heavy losses, but also enjoying successes.

The Carden-Loyd Mk.VI was armed with a water-cooled Vickers 7.7mm infantry heavy machine gun, mounted on an external pivot mount. Its drive mechanism was simple, utilizing some car parts, including a popular Ford T car engine placed between crew seats. Turns were made simply braking one track. An armoured crew compartment had no roof, though head covers were introduced soon in export models. The improved Mk.VIb was more compact, with a new hull and a closed combat compartment.

Since the Carden-Loyd Mk.VI tankette was widely advertised in the world, also for a usage as an armoured tractor, mortar carrier or a gun carrier, it met with a great commercial success, as for its period. An advantage of tankettes was their low price, so they were ideal for creating and training armoured forces. On the other hand, as the future showed, they all had little combat value, and could not be a cheaper alternative of tanks in a battlefield. Apart from the British Army, which used 348 Carden-Loyd tankettes in different variants[1], mostly machine gun carriers, they were sold to at least 16 countries; in small numbers, though[1]. Six countries bought manufacture rights, but none produced the original model in significant numbers. Instead, some countries developed improved derivatives or own tankettes, influenced by Carden-Loyd. First of all it was the USSR, where 3297 of much improved licence tankettes T-27 were produced in 1931-1934. The Italians first built 21 licence tankettes CV-29, then started mass production of an indigenous design CV-33 / CV-35, inspired by Carden-Loyd (Italy found itself in a similar situation to Poland, with armoured divisions consisting mostly of tankettes, which showed little combat value in the Spanish Civil War, then in Africa). Also Czechoslovakia developed an improved derivative tančik vz.33 (name meaning 'small tank', 70 built), and similar own prototype Skoda MU-4. Among these countries was also Poland.

Carden-Loyd in Poland

The Carden-Loyd Mk.VI met with an interest in Poland from the beginning. As soon as in 1929 one tankette was brought and evaluated in Poland. The first show at Rembertow ground took place on 20 June 1929. The first trials were successfull and it was decided to buy 10 tankettes Mk.VI and 5 tracked trailers. They were delivered in August 1929 and given registration numbers: 1143-1152. After divisional manoeuvres in September 1929, it was evaluated, that tankettes fulfill well needs of a reconnaissance vehicle for both infantry and cavalry. Their advantages were: mobility, good obstacle crossing and small dimensions, making them dificult to spot. It was estimated, that they fit better as cavalry reconnaissance vehicles, than newly acquired wz.28 halftrack armoured cars. As a result, the Polish authorities decided to buy a licence for manufacturing Carden-Loyd Mk.VI.

Detailed evaluation revealed faults of the Carden-Loyd tankette, though. First of all, its suspension did not sprung well, and riding was not comfortable, so longer ride was exhausting for a crew, especially off-road. As a result, the suspension in two tankettes was modified in the workshops of the 1st Car Unit, according to a design by Lt. Stanisław Marczewski. The main improvement was adding a semi-elliptical leaf spring between a hull and suspension bogies, and attaching bogies to this spring, instead of a suspension frame. Also return rollers were added. The new suspension improved ride comfort much, and was the most successful design used in Carden-Loyd influenced tankettes. However, instead of producing Carden-Loyd Mk.VI, the Polish authorities decided to work an own, improved model, only generally basing on Carden-Loyd's composition. Probably only two Mark VIs were manufactured in Poland, of mild iron (see below). Carden-Loyd (CL) tankettes were next assigned to the Experimental Armoured-Motorized Group. In the following years, they were used in manoeuvres and for training. Their eventual fate is not known, probably some were broken into parts.

Prototypes of the Polish tankettes

A task of designing the Polish tankette was assigned to the Armoured Weapons Construction Bureau of the Army Engineer Research Institute (BK Br.Panc. WIBI) in Warsaw. Main designers were Maj. Władysław Trzeciak and Cpt. Edward Karkoz, with a cooperation of Edward Habich. The new design was worked in two variants, differing in suspension and drive gear layout. In 1930, the State Engineering Works (PZInż.) in Warsaw built two prototypes: TK-1 with sprocket wheels in the rear and TK-2 with sprocket wheels in front. They were generally modelled after Carden-Loyd in composition, but were completely new designs, more compact and differing in shape. Their suspension was similar to Carden-Loyd suspension modified by S. Marczewski. Tracks were modified and strengthened, made of manganese steel. TK-2 had Ford T engine (like Carden-Loyd), TK-1 - newer Ford A engine. Unlike CL, both were fitted with electric starters. Both vehicles had an open crew compartment and were armed with an air-cooled 7.92 mm Hotchkiss wz.25 machine gun. An abbreviation "TK" has not been explained positively so far - most probably it came from Trzeciak and Karkoz names.

The TK-1 prototype carried a registration number 6006, the TK-2 probably 6007 and another prototype TK-3 probably 6008 [2][8] (According to [1], TK-2 had no. 6008 and TK-3 had 6007, what seems less logical. It is apparent from the photos below, that tank no. 6007 was identical, as the TK-3, but it is possible, that it was a completely rebuilt TK-2). Also, according to [1], two TK prototypes were ordered on 20 March 1930 under a code name "tank X", but according to [2,6,8], tanks "X" were 2 licence copies of Carden-Loyd built of mild iron and completed on 17 May 1930, what seems more reliable.

Prototypes TK-2 and TK-1, then Carden-Loyd Mk.VI with modified suspension and original Carden-Loyd Mk.VI (from left to right) during manoeuvres, probably in 1930. In a background are Ursus A trucks, on the right two Saurer trucks.
[AJ]

In August-September 1930 both TK prototypes took part in divisional manoeuvres, along with Carden-Loyd tankettes. After trials, the construction bureau was ordered to improve the design further. It was fitted with a fully closed combat compartment and given a military designation: "fast tank TK wz.31". Both prototypes were sent to the factory to rebuild them with closed compartments. Also the third improved prototype designated TK-3 was ordered, with a closed compartment and a modified suspension with sprocket wheels in front. Improved prototypes and the TK-3 were completed in March 1931. Probably the TK-2 was completely rebuilt to TK-3 standard, with improved suspension. After trials, prototypes TK-2 and TK-3 were kept in PZInż factory as a production pattern. The prototype TK-1 was later placed as a monument in Armoured Weapons Training Centre in Modlin.

Right: unique photo of the rebuilt TK-1 prototype on a monument, in 1939, after Modlin surrender [photograph Hugo Jaeger]. Note standard camouflage from the late 1930s (it was repainted on a monument). See also another photo of the same author.

TK prototype nr. 6007 in its final form, according to the TK-3 standard (it might be a rebuilt TK-2). Note a horizontal angle of MG fire and two side observation hatches, present in early series TK-3 only. [1]

On 14 July 1931, the Chief of the General Staff accepted the TK-3 prototype, and ordered the first batch of 100 tanks, as a light reconnaissance tank TK-3 (also known simply as the TK). The first information series of 15 tanks (numbers 1154-1168) was built of mild iron plates instead of armour plates[1]. They were completed in August 1931 and just in September sent to divisional manoeuvres. These so-called "iron" tanks were not fit to combat and were later used for training and converting to other designs. The remaining 85 tankettes were made of armoured plates and completed by May 1932. The second batch of 100 tankettes were built by August 1932 - they both were numbered 1169-1353. The last series of 100 tankettes had numbers 1362-1461. A total of 300 TK-3 tankettes, including 15 "iron" ones, were built[1]. This number probably includes also TKF tankettes.

The (most probably) TKF in a museum in Belgrad. Note TKS-style suspension [1] See other photo here

Since the TK-3 was powered with an imported engine Ford A, it was decided to replace it with Polski FIAT-122BC engine, licence-built in Poland. It was first experimentally fitted in the TK-3 nr. 1221 in late 1931 or 1932. In 1933, there was manufactured a small series of tankettes with FIAT engines, designated TKF ("F" for FIAT), but their number is not exactly known - 18 to 22. The information about these vehicles is not clear. Apparently they were included in the last ordered TK-3 series. The production of TKF was discontinued, because an improved model TKS was developed. Probably from 1935 they were modernized using TKS suspension parts and wider tracks, so they had better traction and stronger and more reliable suspension[8] (most significant differences were: an idler wheel suspension and a front frame connector shape). Apart from it, the TKF did not differ externally from the TK-3. A modification of all TK-3 to TKF standard was considered, but abandoned due to costs.

TKS tankette

The TKS prototype nr. 1160 - note the TK-3 suspension, wz.30 (Browning) machine gun, a high muffler and lack of a periscope [1]

In 1933 there started works upon an improved tankette model. The main designer became Edward Habich (after Maj. Trzeciak's death). The new model was generally based upon TK-3 design, but only few parts remained interchangeable. First of all, a hull shape was changed and armour made a bit thicker to increase protection against bullets, and to give a driver a better view. The Ford A engine was replaced with Polski FIAT-122, with a new drive gear. The suspension was strengthened and tracks made 3 cm wider for better traction. The machine gun was mounted in an universal ball mounting with telescopic sights. In a course of production, a significant improvement was a modern reversible periscope for a commander, that enabled all around observation (it was the Polish invention of Rudolf Gundlach(W), next sold to Vickers-Armstrong company and popularized in the world as Tank Periscope Mk.IV (W)). The driver was given a simple periscope in his vision slot. The prototype TKS was converted of one of "iron" TK-3s, nr. 1160, and completed on 1 April 1933. The tank was first designated STK ('special TK'), finally TKS, in documents also written as TK-S. It was also officially designated as the "fast tank wz.33", but designations "wz. .." are never used for serial TK and TKS in any sources, and the Army recognized them just as TK-3 and TK-S.

After successful prototype trials, the PZInż manufactured 20 pre-series tankettes TKS, made of mild iron, in August 1933 (nos. 1492-1511). After minor improvements, the tank was accepted for a serial production on 22 February 1934. The prototype was initially armed with a water-cooled wz.30 machine gun, but in serial tanks it was replaced with the standard air-cooled wz.25 machine gun, despite better reliability of the wz.30 (the reason was a priority of infantry needs).
Starting from the 54th serial tank, the Gundlach periscope was mounted on the roof, what demanded lowering a muffler in order to obtain a clear field of view rearwards. The first series of 83 tanks was completed by June 1934. From the 83rd tank, the 42HP engine Polski FIAT-122AC was changed to the 46HP Polski FIAT-122BC. In the last series, an armour thickness slightly increased. Totally, 282 TKS tankettes were produced until April 1937, including 20 "iron" ones (serial numbers: 1-262, registration numbers: 1492-1594, 1597-1682, 1702-1764, 1799-1814 and some from among 8890-8910)[1]. Apparently 10 additional tankettes were manufactured of funds of the PZInż workers and given to the Army on 15 May 1938[6].

Tankettes with 20 mm gun

Since it was obvious, that tankettes armed with machine guns can not fight against any armoured vehicles, it was proposed to arm some of them with a cannon. After some experiments and trials, in August 1939 it was decided to rearm 80 TKS and 70 TK with Polish 20 mm cannons FK model A. First 10 cannons were delivered in May 1939, the next batch in July. By the war outbreak, only 20 to 24 cannons were mounted in the first series of rearmed TKS. There were also plans to rearm TK tankettes with cannons, what demanded adding a front superstructure, making it similar to the TKS. It was planned to rearm 16 tankettes TK by 25 August 1939, but there is no evidence, that they were completed before the outbreak of the war.